With an elevator, for example, when a person accompanied by a pet such as a dog on a leash boards an elevator car while the pet is still on a landing floor, a car door and a landing door close while the leash is stretched taut so as to straddle the inside of the elevator car and the landing floor and the elevator ascends or descends. As a result, a hand of the person is forcefully pulled by the leash on the pet and may sometimes create a risk of severe injury to a wrist or the like.
A car door of an elevator is mounted with a safety shoe frame which protrudes from an end face of the car door in a closing direction and moves relative to the car door and which is arranged so that when the safety shoe frame bumps into a person or a foreign object during closing of the car door and a force acts on the safety shoe frame, closing operations of the car door and a landing door are reversed to opening operations.
In addition, an arrangement is adopted where an optical beam horizontally transversing an entrance of an elevator car is generated and closing operations of a car door and a landing door are reversed to an opening operation when the optical beam is blocked by a person or a foreign object.
However, conventional foreign object detecting methods that use the aforementioned safety shoe frame or horizontal optical beam are incapable of accurately detecting an elongated foreign object such as a string or a rope.
In consideration thereof, a string-like foreign object is conceivably detected by utilizing a vertical scanning method (refer to Patent Literature 1) involving arranging a light-emitting unit at an upper end position on a vertical line separated by a predetermined distance from an end face in a closing direction of a car door and arranging a light-receiving unit at a lower end position on the vertical line, and detecting light outputted from the light-emitting unit by the light-receiving unit.
In addition, a string-like foreign object is also conceivably detected by utilizing a vertical scanning method (refer to Patent Literature 2) involving arranging a light-emitting unit on a threshold at a position on a vertical line that extends vertically from an abutting position where a pair of car doors abut each other in a fully closed state, arranging a light-receiving unit on a frame above an entrance, and detecting light outputted from the light-emitting unit by the light-receiving unit.
By adopting the vertical scanning methods described above, since an optical scanning line transverses a string during closing of a car door in a state where a string passes through an entrance of an elevator car and stretches at a position with a certain height, the string can be detected based on an output signal of a light-receiving unit.